There's no way to say for sure if that's Cutaneous Marek's or not without testing. If you lose her, send the body to your state lab for testing.
https://www.metzerfarms.com/poultry...SOQBOL9SmaYe8pPbyNJtng_hgK4BPLTXL68fiSihLMZlj
That said, I'd treat the areas like a wound in case that is what it is. Clean the skin really well with saline, povidone iodine or chlorhexidine, then apply a very thin layer of triple antibiotic ointment.
While you are tending to her, check for lice or mites, look inside her ears for any pus or debris Let us know what you find out.
See if you can encourage her to eat some wet poultry feed, bits of egg or fish can also be of interest. Work on hydration. I'd also give her 400IU Vitamin E and 1/4tablet B-Complex daily to for a few weeks to see if this improves the balance.
Observe to make sure her weakness if not being caused by being kept from food/water.